Chapter 9 Compatibilty Testing

Question 1

What does compatibility testing include?

Answer 1

Involves all the steps in the identification and testing of a donor unit and a proposed recipient’s blood.

Question 2

What is crossmatching? What are the test outcomes?

Answer 2

Part of compatibility testing.

Mixing of donor RBCs and recipient serum or plasma (this is referred to as a major crossmatch).

No agglutination or no hemolysis indicates compatibility.

Agglutination or hemolysis indicates incompatibility.

Question 3

What is the main purpose of cross matching?

Answer 3

Serves as a double check of ABO errors.

Provides a second means of detecting unexpected antibodies.

Question 4

When is it ok to perform an immediate spin crossmatching?

Answer 4

When recipient has no evidence of an antibody - either in the current sample OR in the historical record.

Fulfills standards for detecting ABO incompatibility.

Question 5

What is Antiglobulin crossmatching and when is it performed?

Answer 5

All phases (IS, 37C, AHG) are performed if the patient demonstrates a clinically significant antibody either in the current sample OR in the historical record.

Question 6

How may an Antiglobulin crossmatch be performed if the patient has an autoantibody?

Answer 6

Autoabsorbed plasma may be used.

Question 7

What are reasons for unexpected in-compatibilities in immediate spin crossmatch?

Answer 7

1. ABO phenotyping errors from patient ID error or sample labeling error.
2. Unexpected antibodies due to a cold alloantibody (M, P1), Anti-A1 in an A2 patient or cold autoantibody (I, IH).

IS will pick up cold antibodies which are IgM class.

Question 8

What is computer crossmatching and its limitations?

Answer 8

Computer makes final check of the ABO compatibility in the selection of units instead of a serologic IS procedure.

The recipient must not have an antibody (or antibodies) in the current sample or have a history of antibodies.

&

Patient must have had type and screen down 2x’s at CBS before this can be done.

Question 9

What is the computer crossmatching program in MB?

Answer 9

Traceline

Question 10

What is another measure of safety in computer crossmatching?

Answer 10

Barcode labels.

Question 11

Are there still transfusion risks even if an acceptable crossmatch is performed? Why?

Answer 11

Yes, no guarantee.

Adverse transfusion reactions may still occur.

A recipient negative Ab screen may be because titres are very low and therefore a significant Ab goes undetected.

Question 12

What identifiers should the recipient blood sample have?

Answer 12

Two independent identifiers:
1. First and last name
2. PHIN or date of birth.

Question 13

What types should the sample collection tubes be?

Answer 13

EDTA
Could use serum sample tubes.

Question 14

What is the limit on the age of the recipient blood sample (ie crossout date)?

Answer 14

Limit is 3 days if the patient has been recently transfused or is pregnant.

Question 15

What problem samples should not be used?

Answer 15

Hemolyzed samples or samples contaminated with intravenous fluids must be recollected.

Question 16

What is looked in the recipients previous medical records prior to crossmatch?

Answer 16

Current blood ABO and D typing must be compared with results performed over the past 12 months.

Previous records must also be consulted for any significant event related to testing or transfusion.

Question 17

What does it mean to do “repeat testing of donor blood”?

Answer 17

RBCs must be re-typed to confirm the correct ABO labeling (done from segment on bag).

ABO testing is performed on all units.

D testing is performed only on D-negative units.

Weak D testing not required (already done).

Records are kept for 5 years.

Question 18

What is involved in pretransfusion testing?

Answer 18

1. ABO and D typing: discrepancies should be resolved before transfusion.
2. Antibody screen: Unpooled reagent RBCs should be used.
3. Crossmatching: demonstrates ABO incapability and clinical significant antibodies to RBC Ags.

Question 19

What type of blood is given to A, B, AB, and O group in order of preference?

Answer 19

A: A, O
B: B, O
AB: AB, A, B, O
O: O

Plasma is reverse for the 2nd choice, e.g. A: A, AB (not O).
See slide 16.

Question 20

Who should D-negative units be given to?

Answer 20

1. D-negative units should be given to D-negative recipients, especially women of child bearing age.
2. Antigen negative blood should be given if anti-D is formed.

Question 21

What blood groups require given antigen negative units if antibodies to them exist in the recipient?

Answer 21

ABO
Rh
Kell
Duffy
Kidd
Ss and U

Question 22

How are crossmatched blood products tagged?

Answer 22

Requirements for tags on crossmatched donor unit:
1. Patient’s full name and two independent identifiers, (e.g. PHIN and DOB).
2. Name of blood product
3. Unique donor unit number or pool number
4. Unit’s expiration date and ABO and D typing.
5. Interpretation of crossmatching.
6. Technologist’s identification.

Question 23

How many requirements for issuing donor units can you name?

Answer 23

1. Physician’s order.
2. Intended recipient’s 2 independent identifiers. ABO group and D type
3. Requisition form: Patient name and blood product.
4. Compare requisition form w/ donor unit tag.
5. Compare donor unit tag with blood product label.
6. Check blood product’s expiration date.
7. Visual check of unit discoloration? Clot? Abnormal appearance?
8. Documentation of person issuing and person receiving donor unit.
9. Special transfusion requirements.
10. Date and time of issue, unit destination.

Question 24

Under what conditions may unused blood products be reissued (returned)?

Answer 24

1. The closure has not been entered.
2. Unit has been kept between the upper and lower temp. conditions (1 to 10C for RBCs)
3. The unit was stored at room temperature it should be returned within 60 mins or within a time determined by the facility.

Question 25

What is required to for an emergency release of transfusion products?

Answer 25

1. Release must be signed by physician.
2. Tag don donor unit indicating emergency release: compatibility and /or infectious disease.
3. Patient name and identifiers.
4. Donor units number (s), ABO and D typing , expiration date.
5. Retain segments from units for crossmatching.
6. Name of person issuing units.

Question 26

Under what condition will a Dr. order an emergency release of blood for transfusion?

Answer 26

Dr. feels a person will die soon if they don’t receive blood ASAP.

Question 27

What is done in MB for emergency transfusions?

Answer 27

1. Draw blood from the patient and send to CBS to be typed.
2. If there is no time to perform Type and Screen prior o release of RBC’s:
   Give type O positive blood for all patients except children (M&F) <18 years and women < 45 years.
3. Change to type specific once determined by CBS.

Life or death situations is deemed ok to give D pos blood.

Question 28

What is a massive transfusion?

Answer 28

Total volume exchange of blood within 24 hours.

Question 29

What kind of blood is given in an emergency massive transfusion?

Answer 29

Group O, D-negative units are given in an emergency.

If D-neg is unavailable, group O, D-positive blood can be given to D-neg individuals who are not of child bearing age or children.

Question 30

If not an emergency or after emergency has passed what type of blood is given for a massive transfusion?

Answer 30

ABO-identical unit is given once the blood group is established in the recipient.

Red cell units are given first, units of plasma and platelets will also be issued according to hospital protocol.

Question 31

What is the “Maximum Surgical Blood Order Schedule”?

Answer 31

Average number of blood units used for surgical procedures is determined in a facility.

This number is used as the standard blood order for surgical procedures.

Question 32

What may be used as a guide for the number of autologous units that can be donated (or should be)?

Answer 32

The maximum surgical blood order schedule (avg. # of blood units / surgical procedure).

Question 33

What is done instead of reserving blood units for minor surgeries?

Answer 33

Only type & screen is done in advance.

Question 34

Describe what is done in the special crossmatching case of autologous blood?

Answer 34

1. Units donated in advance of surgery if patient is healthy enough.
2. Procedures must be in place to ensure that units are located and transfused to the recipient.
3. The process is monitored manually or through computerized tracking methods.

Question 35

What is done in the case of special crossmatching for infants less than 4 months of age?

Answer 35

1. ABO and D forward typing must be performed.
2. Plasma testing is not necessary.
3. Antibody screening is performed on the infant’s or mother’s sample.
4. If antibody is present, antigen negative units are given.

Question 36

What non-RBC products do not need to be crossmatched?

Answer 36

Frozen plasma
Platelet concentrates
Cryoprecipitate

Because they contain almost no red cells.

Question 37

What should be done for plasma products?

Answer 37

ABO plasma compatible.

Question 38

Do cryoprecipitate and platelet concentrates need to ABO compatible?

Answer 38

May not need to be ABO compatible.

Question 39

What non-RBC products may need to be crossmatched?

Answer 39

Apheresis platelets and granulocyte concentrates if they contain more than 2 mL of RBCs.

Note: WBC not given in Cda except by Hema-Quebec.